title: A study of the physiologic responses to a lung recruitment maneuver in acute lung injury and acute respiratory distress syndrome.
abstract: OBJECTIVE
  To determine the magnitude, duration, and consistency of the effects of lung recruitment maneuvers (RMs) on oxygenation, lung mechanics, and comfort in patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS).
  
  
  METHODS
  We conducted a prospective physiologic study at 3 tertiary-care hospitals. We enrolled 28 consecutive eligible patients with ARDS or ALI and a ratio of P(aO(2)) to fraction of inspired oxygen (P(aO(2))/F(IO(2))) <or= 250 mm Hg while receiving F(IO(2)) >or= 0.50. We performed RMs twice daily for 3 days. The first RM was at 35 cm H(2)O for 20 s. If initial response was equivocal, the clinician immediately administered another RM at a higher pressure (40 cm H(2)O, then 45 cm H(2)O) or for longer period (30 s, then 40 s), in a randomized order. Each patient had up to 6 sets of up to 3 RMs.
  
  
  RESULTS
  Twenty-seven patients met the criteria for ARDS at baseline; 1 had ALI. There was no net effect on oxygenation or pulmonary mechanics following the first or subsequent RMs. The largest rise in P(aO(2)) was from 61 mm Hg to 71 mm Hg, and the largest decrease was 6 mm Hg following the first RM. Augmenting the inflation pressure or duration had no significant effect. These findings precluded analyses about predictors of response or consistency of response. Over the entire study of 122 RMs, 5 patients developed ventilator asynchrony, 3 appeared uncomfortable, 2 experienced transient hypotension, and 4 developed barotrauma that required intervention.
  
  
  CONCLUSIONS
  These results do not support the addition of scheduled RMs to usual treatment for ALI or ARDS.
authors.affiliation: Department of Medicine, McMaster University, Hamilton, Ontario, Canada. meadema@hhsc.ca
authors.forename: Maureen O
authors.initials: MO
authors.lastname: Meade
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Cook
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Griffith
authors.forename: Lori E
authors.initials: LE
authors.lastname: Hand
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Lapinsky
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Stewart
authors.forename: Kieran J
authors.initials: KJ
authors.lastname: Killian
authors.forename: Arthur S
authors.initials: AS
authors.lastname: Slutsky
authors.forename: Gordon H
authors.initials: GH
authors.lastname: Guyatt
mesh_terms: D055371:Acute Lung Injury / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D011175:Positive-Pressure Respiration / Q000379:methods*; D011446:Prospective Studies; D012128:Respiratory Distress Syndrome / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D014109:Total Lung Capacity / Q000502:physiology*; D016896:Treatment Outcome; D014636:Valsalva Maneuver / Q000502:physiology*